The overall goal of this project is to develop a second generation computerized self-help intervention for smoking cessation. The program, LifeSign-II, will incorporate significant enhancements to the current commercial program, LifeSign-I, that will result in a product that is simpler to use and more effective. The LifeSign program utilizes a credit-card sized hand-held computer to implement a scheduled, gradual reduction protocol to extinguish smoking. Modifications that will be developed and tested include: 1) providing a mechanism to adjust the pace of the withdrawal program according to input provided by users, and 2) making the program more sensitive to baseline smoking rates by dividing the baseline period into discrete segments. Withdrawal curves will be then be implemented separately within each segment. This Phase I project will include development of a first generation prototype system and a 10-week feasibility study with 100 smokers. Smokers will be randomly assigned to one of two conditions: LifeSign-I or LifeSign-II. Criteria for feasibility will be statistically significant differences between groups on compliance with withdrawal program; degree of withdrawal symptoms and urges to smoke; and ratings of program speed. During Phase II, a second generation prototype will be developed and evaluated in a large-scale clinical trial. PROPOSED COMMERCIAL APPLICATION: The vast majority of the nearly 50 million smokers in the U.S. prefer self-help interventions for attempts at quitting. The original version of LifeSign has been used by over one million smokers. An improved version of the program, tailored more closely to the needs of smokers, is likely to be a commercially successful product that could have a significant public health impact.